Antibacterial activity of postbiotics metabolites against Mycobacterium avium subsp. paratuberculosis: an in vitro study

BACKGROUND AND OBJECTIVESMycobacterium avium subsp. paratuberculosis (MAP) is a slow-growing bacterium that primarily affects ruminants, causing a chronic disease known as Johne's disease and Crohn's disease in human. Despite extensive research efforts, effective control strategies for this infection remain elusive due to bacterium's ability to evade host immune responses and its resistance to conventional antimicrobial agents. Postbiotics are bioactive compounds produced by lactic acid bacteria during the fermentation process. Postbiotics exhibit antimicrobial properties against pathogenic bacteria and can potentially be utilized as natural alternatives to antibiotics. The aim of this study was to investigated the antibacterial effect of postbiotics derived from Lactobacillus casei and Lactobacillus plantarum in vitro.MATERIALS AND METHODSThe broth susceptibility testing was done using mixed commercialized postbiotics in the Middlebrook ۷H۹ broth. The final concentrations were adjusted to ۵۰, ۲۵, ۱۲.۵, ۶.۲۵, ۳.۱۲۵ mg/mL and then incubated with ۱۰۰ mL of bacterial suspension (approximately to ۱۰۶ CFU). The tubes were incubated at ۳۷°C and the OD۶۰۰ was monitored for ۴۲ days at regular periods and compared with no added postbiotics cultures. The all procedures were repeated at least two times and the lowest concentration of the postbiotics with no detectable bacterial growth (turbidity) was considered the MIC.RESULTS AND DISCUSSIONThe different concentrations of postbiotics showed the antibacterial activity against MAP. The MIC of postbiotics was ۶.۲۵ mg/mL. The probable mechanisms of postbiotics antibacterial activity are due to producing bacteriocins such as Lactocin ۷۰۵ from L. casei and plantaricin from L. plantarum.CONCLUSIONThe results showed that postbiotics could be a practical bioactive compound for prevention and treatment of enteric pathogens such as MAP.

کلیدواژه ها:

Mycobacterium avium subsp. Paratuberculosis ، postbiotics ، MIC ، Lactobacillus casei ، Lactobacillus plantarum